An interdisciplinary model of the natural-human system on the Eastern Shore of Virginia (1880 and 1920): The implications of selected technology and socio-economic factors on system dynamics

This investigation of the natural-human system begins with a review of human history, is advanced by stable isotope data, and explored in depth through detailed systems modeling. More specifically, it examines people as a critical component of the natural system on the Eastern Shore of Virginia during a period of intense technological, social, and environmental change (1880--1920) and compares system dynamics before and after the arrival of the New York, Philadelphia and Norfolk Railroad in 1884, which connected the people, agricultural harvests, and fishing products of the Eastern Shore to large northeastern markets. The Natural-Human System - Eastern Shore of Virginia (NHS-ESVA) model is parameterized with a large body of historical data from the U.S. Census and other historical resources, as well as more traditional biogeophyical perspectives on system dynamics. As such, it simulates energy balances, human population dynamics, terrestrial land use and agricultural harvests, estuarine productivity and fishing harvests, critical technological and economic components influencing farming and fishing activities, and the links between terrestrial and estuarine systems. Simulations of the 1880 system show a farming enterprise that generated enough calories to feed the human population, but which operated at a financial loss and required financial support from fishing activities. In contrast, the 1920 simulations (after the railroad connection to national markets) revealed a system in which farming activities drove an increase in profits by an order of magnitude relative to 1880. Fishing profits in 1920 declined in relative importance due to overfishing, market prices, and the loss of habitat in the Chesapeake Bay because of then-unknown linkages between terrestrial and estuarine systems (i.e., farming practices causing increased erosion, runoff, and nutrient loads, intensified salinity gradients, eutrophication, and benthic anoxia). Carbon and nitrogen isotopes corroborate evidence from historical research and model simulations. This work is presented as an example of interdisciplinary research, in which ecology, isotope geochemistry, history, and economics are incorporated. It has broad implications related to our understanding of coupled natural-human systems, links between terrestrial and estuarine systems, and, perhaps most importantly, as an example of the potential significance of interdisciplinary approaches to complex systems analysis.